set ignition timing with vac gauge

[steve00136]

Well i have read a lot about how you should ignore manufacturers settings which was based on a totally different 1970s leaded fuel and use a vacuum gauge to set timing and not a strobe. I connected my Gunsons vac gauge up after slackening the distributor clamp and as soon as started engine the gauge was showing retarded timing (even though it was set at the prescribed 10deg). I advanced the timing bit by bit. Vac went up and so did tickover speed until it levelled out at 20" so retarded it 1" on the scale which measures in inches. Disconnected and went for a run and a massive difference in acceleration and sounds smoother. On return out of interest i connected my timing strobe and found it was now 20 deg advanced. Seemed a lot to me but will run it and monitor for any pinking.

[Vic Butler]

Not come across this method Steve. This may seem like a daft question but where was the vacuum gauge connected? I presume it was to the vacuum take off point on the carburettor.
I'd like to give it a try, more information please. My BGT has no vacuum advance mechanism on the distributor now.

[steve00136]

I've got a load of info on this is done on my blog at http://www.mymgb.info